For the most part, this is an old habit that no longer applies. Many drivers still believe you need to warm up your car before driving, especially on cooler mornings.
This advice comes from older vehicles, but modern engines are designed differently.
Modern petrol engines are designed to run efficiently almost immediately after starting. Idling to warm up the engine wastes fuel and increases emissions. The fastest way for your engine to reach its optimal operating temperature is by driving gently.
Older diesel engines sometimes needed longer warm-up times, especially in very cold conditions. Modern diesel cars and light commercial vehicles in Australia are equipped with electronic fuel injection and turbochargers, which allow the engine and oil to circulate quickly. Long idling is not necessary and only burns fuel while producing extra emissions.
This approach applies to both petrol and most diesel vehicles and is supported by Australian Government Department of Climate Change, Energy, the Environment and Water
By following this simple advice, you can reduce fuel use, cut emissions and save money while still protecting your vehicle.